A post valve is a valve that is used to control flow of fluid, typically gas, out of a high pressure container or cylinder. Post valves are, for example, common on high pressure oxygen cylinders, and typically have a hand crank mechanism that allows a person to manually open and close the valve to enable or disable the flow of gas from the cylinder. A seat ring is disposed between the valve body and the gas cylinder and either one or two elastomeric O-rings are placed on one or both sides of the seat ring to limit gas escaping from the gas cylinder between a gas cylinder-connecting threaded extension and the gas cylinder.
During operation, the valve actuator is turned, using a handle, knob or other turning mechanism connected thereto, to open a valve orifice within the valve body to thereby allow gas to enter through a passageway within the threaded extension and to flow out of a gas cylinder outlet orifice to the valve actuator. The outlet orifice may be fluidly connected to a device that uses the gas within the gas cylinder, such as a torch or a breathing apparatus.
In prior art post valves, the seat ring is created or machined as a separate part and is placed over a collar on the threaded extension before the post valve is attached to the gas cylinder. In the past, O-rings have been placed on both sides of the seat ring, or without an O-ring between the seat ring and the valve body, and the seat ring has been press fitted onto the collar of the threaded extension. In either case, there is some opportunity for high pressure gas within the gas cylinder to escape through the threaded engagement of the extension and the inner diameter of the seat ring. Further, the manufacturing of the seat ring apart from the valve body creates additional parts and results in a process that has additional manufacturing and assembly steps, which is undesirable.
In a first embodiment of the high pressure post valve described herein, there is disclosed a method of manufacturing a post valve so that the seat ring is integrally formed thereon. The seat ring is integrally formed on the bottom side of the valve body with the gas cylinder-connecting threaded extension extending therefrom. This manufacturing procedure results in a post valve that provides no opportunity for gas to escape between the seat ring and the valve body. The manufacturing process includes starting with round metal bar stock, which is less expensive than the square or rectangular bar stock now used to machine the valve bodies, and cutting or etching away the outer diameter of the round metal stock to create the square or rectangular portions of the valve body The seat ring is turned or left to be circular. The threaded extension also is turned to the proper diameter. Thereafter, exterior holes (such as the outlet orifice) are created by side cuts or drill cuts. Next, the interior sections of the valve body are machined and the threads are cut into the threaded extension. Because this manufacturing process starts with the less expensive round bar stock, the entire manufacturing process is cheaper than the traditional process which starts with square or rectangular bar stock and uses a separate, press fitted or floating circular seat ring.
Another serious disadvantage of extant post valves for connection to a high pressure gas supply is that sometimes when the valve is opened, high pressure gas carries solid particulate materials into a valve cavity of the valve actuator (such as metal particles or dust from the gas cylinder). These high speed particles strike against the polymeric valve seat sealing material, thereby creating sufficient heat to ignite the valve seat material. This is potentially very dangerous to a patient receiving oxygen, and to those surrounding the high pressure gas cylinder.
Typical in the prior art, the actuator is coupled to a valve seat, typically made of brass, disposed in a valve chamber. Longitudinal movement of the actuator causes the valve seat to move toward or away from a conical gas inlet orifice. When the valve seat is moved away from the gas inlet orifice, gas under high pressure enters into the valve chamber through a passageway within the threaded extension and through the gas inlet orifice. The actuator valve seat includes a circular cavity. Valve seating material, typically a polymer or elastomeric material, is disposed within the cavity and, when the post valve is closed, comes into sealing contact with the conical gas inlet orifice to prevent gas from entering into the valve chamber. The polymer or elastomeric material is used at the seating surface of the orifice because it is softer than brass and thus provides a better seal. However, when the actuator is turned to cause the valve seat to move away from the orifice, gas under very high pressure flows through the orifice and comes into direct contact with the valve seat material 42. Impurities in the gas, such as particles, will hit the valve seat material directly at very high speeds. In some cases, the energy in these particles is enough to cause ignition of the valve seat material, which may lead to the combustion of the post valve and down stream components.
As disclosed herein in the second embodiment, the improved valve design includes the valve seat material 50 disposed to surround the gas inlet orifice. In this configuration, the bottom surface of the annular ring comprising the actuator valve seat provides sealing contact with the valve seat material in an area surrounding, and preferably below, the inlet orifice so that impurities within the gas flowing at high speeds through the orifice first hit a metal surface in the valve cavity, which has a much higher ignition temperature than the valve seat material. This configuration reduces the likelihood of impurities within the gas causing ignition with the post valve.